Latency Management

ABSTRACT

A method for use in an automated wireless industrial system comprising a device configured to act as a control node and at least one field level device, wherein the method comprises: issuing a control communication; inserting at least one time delay (tk) to the control communication; noting the communication time (TCL) for the communication; comparing the time for communication (TCL) to an expected time for communication (TR); and determining if any of the at least one time delay (tk) should be adapted, and if so, adapting at least that time delay.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/771,286 filed 10 Jun. 2020, which is a U.S. National PhaseApplication of PCT/EP2017/082457 filed 12 Dec. 2017. The entire contentsof each aforementioned application is incorporated herein by reference.

TECHNICAL FIELD

This application relates to a wireless communications device, a methodand a computer-readable storage medium for improved latency management,and in particular to a wireless communications device, a method and acomputer-readable storage medium for improved latency management inautomated wireless industrial communication.

BACKGROUND

More and more industries are becoming automated, and the industrialautomation architecture is often referred to as the automation pyramid,basically having three levels. The top level is the management level,where Manufacturing Execution Systems (MES) resides. MES manages amongother things resource allocation, operations scheduling, producttracking and maintenance management.

Below the management level is the automation level, where there arecontrol systems like Programmable Logic Controllers (PLC), DistributedControl Systems (DCS), supervisory systems such as Supervisory ControlAnd Data Acquisition (SCADA) systems and Human Machine interfaces (HMI).PLC systems are used for manufacturing automation. DCS systems are usedfor process automation. SCADA systems are used for centralizedsupervision. HMIs are used for enabling local supervision and control.

Below the automation layer is the field layer having the actual sensorsand actuators which provide access to, for controlling and/or forsensing/reading, the physical processes.

The layers communicate with one another through commands and datapoints, such as for reading sensor values, executing actuator commandsand retrieving status information.

The communication techniques used between the various layers differwidely from system to system, but generally the higher up in thepyramid, the higher the abstraction level of the communication standardbeing used. For example, communication with the Management layer isusually through IP (Internet Protocol) communication. Communication withthe Automation layer is usually through Ethernet communication protocolsand the Field layers traditionally use various fieldbuses.

In the automation industry, there are strict requirements on thecommunication latency, not only on the average, but especially for themaximum latency tolerable. As the automation is designed to monitorand/or control various physical processes, there is of courserequirements that some monitoring/control steps do not take too muchtime, such as longer than the corresponding physical process requires.In such case, the automation will be doomed to fail.

As wireless communication grows in popularity also for the automatedindustry many of these field buses are being replaced by wirelesstechnologies such as Wi-Fi. ZigBee, Bluetooth, WirelessHART (based onIEEE 802.15.4), ISA100.11a (based on IEEE 802.15.4) and differentcellular technologies such as Long term Evolution (LTE) and GlobalSysteme Mobile (GSM).

As is known, wireless communication is exposed to a much wider range ofinterference and disturbance, and as a shared physical channel (thespectrum between different frequencies) is shared, the speed ofcommunication also varies with the actual deployment. This is one of themajor reasons why automating using wireless systems is so difficult. Itis nearly impossible to predict how the system will behave in allenvironments, how it will be affected by changes and how it may bescaled. For example, a truck carrying a load of metal parts driving into a factory, will impact the radio frequency environment of the factoryto a large extent, possible interfering with the devices at the fieldlevel of the automation process causing a delay or increase in latencythat may be unacceptable.

In view of the problems and shortcomings indicated above, there is aneed for an improved manner of managing the latency in automatedwireless industrial processes so that such increases in latencies isavoided.

SUMMARY

It is therefore an object of the teachings of this application toovercome or at least mitigate one or more of the problems andshortcomings listed above and below by providing a method for use in anautomated wireless industrial system comprising a device configured toact as a control node and at least one field level device, wherein themethod comprises: issuing a control communication; inserting at leastone time delay (tk) to the control communication; noting thecommunication time (TCL) for the communication; comparing the time forcommunication (TCL) to an expected time for communication (TR); anddetermining if any of the at least one time delay (tk) should beadapted, and if so, adapting at least that time delay.

It is also an object of the teachings of this application to overcome orat least mitigate one or more of the problems and shortcomings listedabove and below by providing a device comprising a processor arrangementand a wireless interface, wherein said processor arrangement isconfigured to act as a control node by: issuing a control communicationto which at least one of time delay (tk) is inserted; noting thecommunication time (TCL) for the communication; comparing the time forcommunication (TCL) to an expected time for communication (TR); anddetermining if any of the at least one of time delay (tk) should beadapted, and if so, adapting at least that time delay.

In one embodiment, the device is configured for use in a wirelessindustrial system.

It is moreover an object of the teachings of this application toovercome one or more of the problems and shortcomings listed above byproviding a computer readable storage medium encoded with instructionsthat, when executed on a processor, perform the method referred toabove.

Other features and advantages of the disclosed embodiments will appearfrom the following detailed disclosure, from the attached dependentclaims as well as from the drawings. Generally, all terms used in theclaims are to be interpreted according to their ordinary meaning in thetechnical field, unless explicitly defined otherwise herein. Allreferences to “a/an/the [element, device, component, means, step, etc.]”are to be interpreted openly as referring to at least one instance ofthe element, device, component, means, step, etc., unless explicitlystated otherwise. The steps of any method disclosed herein do not haveto be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in further detail under reference to theaccompanying drawings, in which:

FIG. 1 shows a schematic overview of the components of a wirelesscommunications device according to one embodiment of the teachings ofthis application;

FIG. 2 shows a schematic overview of an automated wireless system inwhich an wireless communication device according to FIG. 1 is utilizedaccording to one embodiment of the teachings of this application;

FIG. 3 shows a schematic view of

according to one embodiment of the teachings of this application;

FIG. 4 shows a flowchart for a general method of controlling atelecommunications device according to the teachings herein;

FIG. 5 shows a schematic view of an example haptic telecommunicationsdevice system according to one embodiment of the teachings of thisapplication; and

FIG. 6 shows a schematic view of a computer-readable medium according tothe teachings herein.

DETAILED DESCRIPTION

The disclosed embodiments will now be described more fully hereinafterwith reference to the accompanying drawings, in which certainembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided by way of example so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. Like numbers refer to like elements throughout.

FIG. 1 shows a schematic overview of a wireless communications device100 or User Equipment (UE) according to one embodiment of the presentinvention. The UE may be a robotic tool, an actuator, a sensor or otherautomated industrial device.

The UE 100 comprises a processor arrangement 110 which is configured tocontrol the overall functionality and also specific functions of the UE100 such as by executing computer program instructions loaded into orstored on a memory 120 connected to or being part of the processorarrangement 110. The processor arrangement 110 may comprise one or moreprocessors or other logic programmable circuits for combined orindividual execution of a task or application. However, for the purposeof this application they will be seen as being the one and sameprocessor arrangement 110. The processor arrangement 110 is connected toor comprising the memory 120 for storing computer instructions and alsodata to be processed by the computer instructions when executed by theprocessor arrangement 110. The memory 120 may comprise one or severalmemory circuits, possibly arranged in a hierarchy. One or more of suchmemory circuits may be comprised in the processor arrangement 110. Forthe purpose of this application the memory circuits will be regarded asone memory 120.

The processor arrangement 110 may also connected to a Human MachineInterface 130 for receiving input from a user and for presenting data orother information to the user.

The processor arrangement 110 is also connected to a communicationsinterface 140, such as a Radio frequency interface. The RF interface 140may be configured to operate according to a long range standard, such asa cellular network standard GSM, LTE or a 5G standard. The RF interfacemay alternatively or additionally be configured to operate according toa short range standard, such as a Bluetooth®, IEEE802.11b (WiFi™),IEEEE802.16, ZigBeer™. WirelessHART (based on IEEE 802.15.4), ISA100.11a(based on IEEE 802.15.4) or NFC™ (Near Field Communication) standard.

The communications interface 140 enables a UE 100 to communicate withother devices, for example in the automation layer.

The UE may also comprise a power source 150, such as a battery or apower feed.

FIG. 2 shows an example of a communication system 200 used for automatedwireless industry. The levels of the automation pyramid are showndemarcated by dotted lines.

In the MES layer there is a device 210 implementing a MES. The MESdevice 210 is wirelessly communicating with at least one device 220 inthe automation layer, such as a PLC. The PLC device 220 is in turncommunicating with one or several devices 230 in the field layer, suchas sensors or actuators. For the purpose of this application, nodifference will be made between the various field devices, or theautomation or management devices. As would be apparent to a skilledperson, which device is actually connected to which device is highlydependent on the context of the process being automated and may varywidely. Also, a device may be executing in two or more layerssimultaneously, having different software or hardware modules handlingvarious tasks, possibly in different layers of the automationarchitecture model.

FIG. 3 shows a different schematic view of the automated industryprocess system 200 of FIG. 2, where a controller loop module is arrangedto be implemented by a processor arrangement 110 of a device 100. Thedevice 100 may be a device in the management layer (210) or in theautomation layer (220), or even in the field layer (230). The device 100may even be a base station.

The control node 310 is arranged to communicate with one or more fielddevices 230 (such as sensors and/or actuators). The time t_(i) forcommunicating with a field device i corresponds to a first transmissiontime t_(iT) (for transmitting (T) a request to the field device i), aprocess time t_(p), and a reception time t_(iR) (for receiving (R) theresponse from the field device i). Expressed as a formula:

t _(i) =t _(iT) +t _(iP) +t _(iR).

The control node may be arranged to perform a control loop of theassociated field devices to ensure that the system it represents isacting according or performing to its requirements. For example, if anexample system is set up so as to receive input from a sensor (afterprompting) and then commanding for example two actuators to perform eacha task, the total time this control loop would take TCL equals the timeto prompt the sensor plus the time to execute the two actuators' tasks,that is the longer of the time to execute each of these two tasks.

For the example of FIG. 3, where the control node 310 performs a controlloop on the sensor S1 and the actuators A1 and A2 we get that the timefor the control loop TCL equals:

TCL=t _(S1)+MAX(t _(A1) ;t _(A2))=>TCL=t _(S1T) +t _(1P) +t _(S1R)+MAX(t_(A1T) +t _(A1P) +t _(A1R) ;t _(A2T) +t _(A2P) +t _(A2R))

Assuming the processing time is negligent compared to thetransmission/reception time, or possibly indistinguishable from thetransmission/reception times (such as the processing time beingunknown), we get:

TCL=t _(S1T) +t _(S1R)+MAX(t _(A1T) +t _(A1R) ;t _(A2T) +t _(A2R)).

For maintaining a stable process, it is imperative that the time of sucha control loop falls under the time requirements TR for the process.

The inventors have realized that by adding a variable time delay to eachtransmission and possibly to each reception (the reception being atransmission in the opposite direction), the latency of the controlsystem may become more stable, more predictable and more manageable. Thetime delay may be added or inserted in to the communication by halting acommunication interface and/or a processor arrangement's execution ofthe relevant instructions for a time equalling the time delay. Byvarying the delay and measuring how the time for a control loop matchesthe requirements (and setting the requirements to slightly less than theabsolute maximum time requirement), the latency of the system may bemanaged by adjusting the delay to a lower value, if the total time for acontrol loop exceeds the requirement, and by adjusting the delay to ahigher value, if the total time for a control loop does not exceed therequirement. The requirement may be the actual timelimit after which thesystem may start to experience timing errors, or the requirement may bea (safer) threshold level, where the risk of timing errors is lower, andat which the system is more likely to operate without difficulties.

By adding such a variable, air space is also introduced into the systemenabling a time sharing of a channel.

FIG. 4 shows a schematic view of how the time delays tk may be added tothe communication times, exemplified by the communication time forsensor S1. In FIG. 4, three main scenarios are shown: A) when the delayis simply added to the total time for sensor S1; B) when thecommunication time is seen as the sum of the transmission time and thereception time and a delay is added to each of these; and C) when thecommunication time is seen as involving a processing time, and a delayis added to the transmission time, the reception time and/or to theprocessing time.

Depending on which component that is used to add the delay, one orseveral of the scenarios of FIG. 4 may be used. For example, if it isthe receiving control node that adds the delay tk, then scenario A) ismost likely the best option to use, where a simple delay is added uponreception of the response to a query T=t_(S1)+tk, where T is the timefrom transmission to reception, and tk is the time delay.

In another example, where the communication interfaces of respectivedevices included in the control loop (sensors, actuators . . . ) areadding the delays, scenario B is most likely the best option to usewhere a simple delay may be added either upon each transmission of adata package, and/or upon reception of a data package, whereT=t_(S1)=t_(S1T)+tk+t_(S1R)+tk.

In another example, where the processor arrangements 110 are adding thedelays, one possibility is where a delay is also added by the processorarrangement 110 of the field device to the processing time. This may bedone in addition to the delays added to the transmission times, shown inscenario C2, or as an alternative, shown in scenario C3. Anotherpossibility is where both processor arrangements 110 (the processorarrangement 110 of the field device, and the processor arrangement 110of the control node) add a delay as shown in scenario C4. Otherpossibilities are to only add the time delay to the transmission time orto only add the time delay to the reception time.

It should be noted that although the delays are shown as being one delaytk, they may differ. For example, the time delay added to thetransmission time may be different from the time delay added to thereception time.

As a skilled person would realize, the overall effect of which scenariois used may vary on the given implementation and in some cases acombination of several scenarios may be used for different and/or forthe same control nodes.

By adding the delay tk at various points in the control loop. i.e. atdifferent times, opens up airspace at different time for time sharing ofthe channel.

It should also be noted that the time delays to be added at differentpoints do not need to be the same, even though illustrated as such inthe figures.

In the following the description will focus on scenario A) where a delay(possibly representing a total delay) is added to regulate thecommunication time to substantially equal the required time TR.

The control node thus performs a control loop and notes the time for thecontrol loop TCL. This may be done regularly, such as every 1 second,every 1/10 seconds, or every 1/100 seconds. The control loop may also bechecked regularly or continuously by simply monitoring the communicationtimes with the field devices. It may also be done if a disturbance isdetected. Such a disturbance may be detected through a delay or changein response times. Usually such a delay or change in response timeswould be rather sudden, unlike a gradual change over time.

Starting with a default time delay, the time for a control loop (TCL) ismeasured. The default time delay is in one embodiment 0 seconds, i.e.the control loop time is measured without any delays added. In oneembodiment the default time delay is greater from 0 seconds, enabling adesigner to implement a system, that based on experience or simulationsusually end up having a time delay larger than 0 thereby enabling for afaster adaptation of the system.

If the time for the control loop is lower than the time requirement(TCL<TR) the time delay is adjusted to a higher value. If the time forthe control loop is higher than the time requirement (TCL>TR) the timedelay is adjusted to a lower value.

The time delay to be added (or expressed differently, the differencebetween an actual transmission time and an expected or wantedtransmission time) may be seen as a measurement of how “healthy” (i.e.free of disturbances and interference) the radio frequency environmentis, where a long or high time delay indicates a low level ofinterferences, and where a high level of interferences will lead to ashort time delay. The time delay may also be seen as a measurement ofhow loaded the communication system is, where a long or high time delayindicates a low total load, and where a high total load will lead to ashort time delay.

In one embodiment the processor arrangement 110 of the device 100 may beconfigured to monitor the latency of the automated process to ensurethat it is running smoothly and as expected, by adapting the delay andtherefore also the expected response times.

In one embodiment the processor arrangement 110 of the device 100 may beconfigured to determine that the radio frequency environment and/or loadon the communication system is such that fast and critical systems maynot be able to operate correctly, and thereby adapt them (increase theirexpected and/or required communication times) or perform a gracefulshutdown before any system crash can occur. A time delay tk fallingbelow a threshold value may be used as an indicator of a bad environmentand/or a high load that is high or reaching a threshold level.

In one embodiment, the rate of change of the time delay to be added maybe used as an indicator. A rapidly falling (or decreasing) time delaymay indicate a radio environment going bad and/or a high load that isrising or reaching a threshold level and indicate to the processorarrangement 110 to cause a shutdown of one or several systems so thatthey can be switched off gracefully before any crashes occur. Theprocessor arrangement 110 may thus be configured to detect that the rateof change is above a first rate threshold, and cause a shutdown of atleast one device.

A slowly changing time delay to be added may indicate that anothercommunication parameter should or could be changed. The processorarrangement 110 may thus be configured to detect that the rate of changeis below a second rate threshold, and adapt a parameter accordingly. Oneexample is the factor by which the time delay is changed. Anotherparameter to be changed could be parameters of the communication channelused.

In one embodiment the processor arrangement 110 of the device 100 may beconfigured to determine that the radio frequency environment orcommunication load is such that more devices may be added or not. Suchan embodiment may be useful for running dimension simulations or tests.

In one embodiment the time delay tk is changed to proportional to thedifference between the time for the control loop and the expected time.In one such embodiment, the time to be added may be increased by aportion of the difference, for example 10%, 20%, 25%, 30%, 33%, 40%,50%, 60%, 67%, 70% 75%, 80%, 90% or 95% of the difference.

Another example is where the time delay is changed in proportion to thedifference, where a large difference gives a large change to enable afast adaptation without surpassing the critical time restraints. Forexample the time delay is changed proportional to the quota of the timedifference and the time delay or vice versa. So that if the time delayis large compared to the time difference, a small change is made. If thetime delay is small compared to the time difference, a large change ismade.

In one embodiment, the time delay is changed incrementally. In such anembodiment, a check may be performed to see if the resulting time delaywould result in a communication time exceeding the time requirement andif so, signal a shutdown of a system or a warning.

It should be noted that, as several time delays may exist in one loop(confer for example scenarios B and C) the teachings herein includebasing determinations on one, a subset or all of the time delays, andfor adapting one, a subset or all of the time delays. Monitoring,comparing and/or adapting/changing a time delay, should thus beconsidered to include monitoring, comparing and/or adapting/changing atleast one time delay.

FIG. 5 shows a flowchart for a general method according to herein formanaging the latency of an automated wireless industrial process such asin FIGS. 2 and 3.

A control loop (possibly being a test script or a proper communication)is issued 510 by a control node. At least one time delay (referred aboveto as tk) is added or inserted 520 to the time for the communication, byhalting a communication interface and/or a processor arrangement'sexecution of the relevant instructions for a time equalling the timedelay. As the control loop is received, the time for the communication(including the time delay) is noted or determined 530. The time for thecommunication (referred above to as TCL) is compared 540 to an expected(or wanted) communication time (referred to above as TR) to determine550 whether the time delay (referred above to as tk) should be adaptedor not. If it is determined that the time delay should be adapted, thetime delay is adapted 560 and a new or further control loop may be sentout. It may also be determined 570 that a system parameter should bechanged or adapted based on the comparison and if so, changing oradapting the parameter 575 accordingly. A parameter may for example beadapted by adjusting a value of the parameter. A parameter may bechanged by replacing the parameter. This may be optional as indicated bythe dashed lines.

Based on the comparison it may also be determined that a warning or ashutdown should be effected 580 and if so, shutting down or warning 585accordingly.

FIG. 6 shows a schematic view of a computer-readable medium as describedin the above. The computer-readable medium 60 is in this embodiment adata disc 60. In one embodiment the data disc 60 is a magnetic datastorage disc. The data disc 60 is configured to carry instructions 61that when loaded into a processor arrangement 110, such as a processorsuch as the controller of the device 100 of FIG. 1, execute a method orprocedure according to the embodiments disclosed above. The data disc 60is arranged to be connected to or within and read by a reading device62, for loading the instructions into the processor arrangement 110. Onesuch example of a reading device 62 in combination with one (or several)data disc(s) 60 is a hard drive. It should be noted that thecomputer-readable medium can also be other mediums such as compactdiscs, digital video discs, flash memories or other memory technologiescommonly used. In such an embodiment the data disc 60 is one type of atangible computer-readable medium 60.

The instructions 61 may also be downloaded to a computer data readingdevice 100, such as the processor arrangement 110 or other devicecapable of reading computer coded data on a computer-readable medium, bycomprising the instructions 61 in a computer-readable signal which istransmitted via a wireless (or wired) interface (for example via theInternet) to the computer data reading device 100 for loading theinstructions 61 into a processor arrangement 110. In such an embodimentthe computer-readable signal is one type of a non-tangiblecomputer-readable medium 60. The instructions may be stored in a memory(not shown explicitly in FIG. 6, but referenced 120 in FIG. 1) of thecomputer data reading device 100.

The instructions comprising the teachings according to the presentinvention may thus be downloaded or otherwise loaded in to a device 100in order to cause the device 100 to operate according to the teachingsof the present invention.

References to computer program, instructions, code etc. should beunderstood to encompass software for a programmable processor orfirmware such as, for example, the programmable content of a hardwaredevice whether instructions for a processor, or configuration settingsfor a fixed-function device, gate array or programmable logic deviceetc.

The invention has mainly been described above with reference to a fewembodiments. However, as is readily appreciated by a person skilled inthe art, other embodiments than the ones disclosed above are equallypossible within the scope of the invention, as defined by the appendedpatent claims.

What is claimed is:
 1. A method for use in a wireless system comprisinga control node and at least one field-level device, wherein the methodcomprises: monitoring a time for a control loop performed on a recurringbasis, the control loop involving wireless communication between thecontrol node and the at least one field level device; and adjusting anintentional delay inserted into the control loop, to regulate the timefor the control loop according to a required time.
 2. The methodaccording to claim 1, wherein the required time is below an actual timelimit for performing the control loop.
 3. The method according to claim1, wherein the time for the control loop unintentionally varies independence on interference in a radio frequency environment of thewireless system, and wherein adjusting the intentional delay comprisesadjusting the intentional delay in an inverse relationship withunintentional variations in the time for the control loop.
 4. The methodaccording to claim 1, wherein the time for the control loopunintentionally varies in dependence on loading of the wireless system,and wherein adjusting the intentional delay comprises adjusting theintentional delay in an inverse relationship with the unintentionalvariations.
 5. The method according to claim 1, wherein adjusting theintentional delay comprises adjusting the intentional delay to a highervalue responsive to the time for the control loop being lower than therequired time and adjusting the intentional delay to a lower valueresponsive to the time for the control loop being higher than therequired time.
 6. The method according to claim 1, further comprisinginitiating a controlled shutdown of a system associated with the controlloop, in response to the intentional delay falling below a definedthreshold.
 7. The method according to claim 6, wherein the systemassociated with the control loop is an industrial system whose operationdepends on the control loop.
 8. The method according to claim 1, furthercomprising initiating a controlled shutdown of a system associated withthe control loop, in response to a rate of change or a step size ofadjustments made to the intentional delay exceeding a defined threshold.9. The method according to claim 1, wherein the intentional delaycomprises one or more delays imposed at the control node or thefield-level device or both the control node and the field-level device.10. The method according to claim 9, wherein the one or more delayscomprise any one or more of: delaying one or more control messages goingbetween the control node and the field-level device for performance ofthe control loop, and delaying one or more processing operations at thecontrol node or the field-level node or both, for performance of thecontrol loop.
 11. A control node of a wireless system comprising atleast one field-level device and the control node, the control nodecomprising: a wireless interface configured for communicating with theat least one field-level device; and processing circuitry configured to:monitor a time for a control loop performed on a recurring basis, thecontrol loop involving wireless communication between the control nodeand the at least one field-level device; and adjust an intentional delayinserted into the control loop, to regulate the time for the controlloop according to a required time.
 12. The control node according toclaim 11, wherein the required time is below an actual time limit forperforming the control loop.
 13. The control node according to claim 11,wherein the time for the control loop unintentionally varies independence on interference in a radio frequency environment of thewireless system, and wherein the processing circuitry is configured toadjust the intentional delay in an inverse relationship withunintentional variations in the time for the control loop.
 14. Thecontrol node according to claim 11, wherein the time for the controlloop unintentionally varies in dependence on loading of the wirelesssystem, and wherein the processing circuitry is configured to adjust theintentional delay in an inverse relationship with unintentionalvariations in the time for the control loop.
 15. The control nodeaccording to claim 11, wherein the processing circuitry is configured toadjust the intentional delay to a higher value responsive to the timefor the control loop being lower than the required time and adjust theintentional delay to a lower value responsive to the time for thecontrol loop being higher than the required time.
 16. The control nodeaccording to claim 11, wherein the processing circuitry is furtherconfigured to initiate a controlled shutdown of a system associated withthe control loop, in response to the intentional delay falling below adefined threshold.
 17. The control node according to claim 16, whereinthe system associated with the control loop is an industrial systemwhose operation depends on the control loop.
 18. The control nodeaccording to claim 11, wherein the processing circuitry is furtherconfigured to initiate a controlled shutdown of a system associated withthe control loop, in response to a rate of change or a step size ofadjustments made to the intentional delay exceeding a defined threshold.19. The control node according to claim 11, wherein the intentionaldelay comprises one or more delays imposed at the control node or thefield-level device or both the control node and the field-level device.20. The control node according to claim 19, wherein the one or moredelays comprise any one or more of: delaying one or more controlmessages going between the control node and the field-level device forperformance of the control loop, and delaying one or more processingoperations at the control node or the field-level node or both, forperformance of the control loop.